ASTM_C_522_-_03_2016.pdf

Designation:C52203(Reapproved 2016)Standard Test Method forAirflow Resistance of Acoustical Materials1This standard is issued under the fixed designation C522;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of airflowresistance and the related measurements of specific airflowresistance and airflow resistivity of porous materials that can beused for the absorption and attenuation of sound.Materialscover a range from thick boards or blankets to thin mats,fabrics,papers,and screens.When the material is anisotropic,provision is made for measurements along different axes of thespecimen.1.2 This test method is designed for the measurement ofvalues of specific airflow resistance ranging from 100 to10 000 mks rayls(Pas/m)with linear airflow velocities rang-ing from 0.5 to 50 mm/s and pressure differences across thespecimen ranging from 0.1 to 250 Pa.The upper limit of thisrange of linear airflow velocities is a point at which the airflowthrough most porous materials is in partial or completetransition from laminar to turbulent flow.1.3 A procedure for accrediting a laboratory for the pur-poses of this test method is given in Annex A1.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4.1 Table 1 is provided for user to convert into cgs units.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E384 Test Method for Microindentation Hardness of Mate-rialsC634 Terminology Relating to Building and EnvironmentalAcousticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:The definitions used in this test method arecontained in Terminology C634.3.2 Definitions of Terms Specific to This Standard:Thefollowing items have been modified to exclude alternatingflow.3.2.1 airflow resistance,R;mks acoustic ohm(Pas/m3)the quotient of the air pressure difference across aspecimen divided by the volume velocity of airflow through thespecimen.3.2.2 airflow resistivity,r0;mks rayl/m(Pas/m2)of ahomogeneous material,the quotient of its specific airflowresistance divided by its thickness.3.2.3 lateral airflow resistivity of an anisotropic homoge-neous material,the airflow resistivity when the direction ofairflow is parallel to the face of the material from which the testspecimen is taken.3.2.4 specific airflow resistance,r;mks rayl(Pas/m)theproduct of the airflow resistance of a specimen and its area.This is equivalent to the air pressure difference across thespecimen divided by the linear velocity of airflow measuredoutside the specimen.3.2.5 transverse airflow resistivity of an anisotropic ho-mogeneous material,the airflow resistivity when the directionof airflow is perpendicular to the face of the material fromwhich the test specimen is taken.3.3 Application of Terms:3.3.1 The term airflow resistance can be applied to speci-mens of any kind.3.3.2 The term specific airflow resistance has meaning onlywhen applied to a specimen of uniform thickness that ishomogeneous in directions parallel to its surface but notnecessarily homogeneous in the direction of airflow perpen-dicular to its surface.3.3.3 The term airflow resistivity has meaning only whenapplied to a specimen that is homogeneous in directionsparallel to a and perpendicular to its surface but not necessarilyisotropic.1This test method is under the jurisdiction ofASTM Committee E33 on Buildingand Environmental Acoustics and is the direct responsibility of SubcommitteeE33.01 on Sound Absorption.Current edition approved April 1,2016.Published April 2016.Originallyapproved in 1963.Last previous edition approved in 2009 as C522 03(2009)1.DOI:10.1520/C0522-03R16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.4 Symbols:3.4.1 P=air pressure difference across test specimen,Pa.3.4.2 U=volume velocity of airflow through the specimen,m3/s.3.4.3 u=U/S=linear velocity of airflow outside thespecimen,m/s.3.4.4 S=area of specimen,m.23.4.5 T=thickness of specimen,m.4.Summary of Test Method4.1 This test method describes how to measure a steady flowof air through a test specimen,how to measure the air press